Usage application of a machine for recycling gypsum plaster board

ABSTRACT

Usage application of a per se known in the art continuous-operation machineor the recycling of gypsum plaster board. A coarsely pre-pulverized material is introduced into a continuous-operation machine and, within the continuous-operation machine, the waste material 20 is guided along a product-cycle in a spiral-shaped fashion through the container 4 The tools 18, 18&#39;, 18&#34;, 18&#39;&#34;, which are arranged along an axial length on the shaft 7, rotate in a Froude number region Fr≧7 and break-up the pre-pulverized waste material 20 to a sufficient extent that a grain spectrum is produced which effectively facilitates the use of calcination devices.

BACKGROUND OF THE INVENTION

The invention concerns a usage application of a continuous-operationmachine, consisting essentially of a horizontally positioned cylindricalcontainer having a product feed chute and a product exit chute, adriveable shaft in the container, preferentially mounted to front walls,tools mounted on the shaft, which are directed radially outward from theshaft, whereby the shaft is operated in the Froude number region FR≧7.

A continuous-operation machine of this type has become known through thebrochure "Befeuchtungsmischer" (wetting-mixer) WD 12.79 SM/Rd-e 47.1500Gebruder Lodige Maschinenbau GmbH, Paderborn, Germany, 1979.

The known rapid continuous-operation and compact machine is designed forlarge through-put. It processes, as is known in the art, powdered andshort-fibered material with liquid media and is utilized in the area ofsolid-liquid mixing. The known machine is distinguished, on the onehand, by a good mixing precision at short dwell times and largethrough-put capacities are possible with small machine dimensions.

The tools mounted onto the shaft rotate in a Froude number range of7-20, whereby the Froude number is formed from the quotient of therevolution frequency n and the critical revolution frequency n_(c).##EQU1##

In this revolution frequency range the product flowing into the machineis subjected to centrifugal forces by the tools which press the productagainst the inner wall of the container. The product passes through themachine in a product-cycle. In this fashion, the known mixing processesoccur.

When manufacturing gypsum plaster board, a certain amount ofunmarketable waste always occurs which consists essentially of damagedboard or board which is not to specifications. The waste occurspartially directly following binding or sealing, and partially afterdrying of the bound boards. In the first case the waste comprises 30 to40% moisture and in the second case the waste material is practicallycompletely dry. The amount of waste material depends on the particularmanufacturing procedure and differs; this amount lies in general between2 and 8% of the product bulk and reaches, in extreme cases, even 10%.

In practice the re-introduction of this waste as a secondary rawmaterial back into the production process is known in the art. Towardsthis end one had initially coarsely pulverized the boards. Thispre-pulverized material is a mixture between gypsum chips and cardboardshreds assuming sizes up to the size of a hand on which gypsum residueis firmly bonded. With the gypsum plaster boards which are most oftenused having an areal weight of approximately 8 kilograms per m², thefraction of paper is between 4.5 to 5%, and with boards having an arealweight of approximately 11 kilograms per m², from 3.4 to 3.8%. Apractically acceptable separation of the paper and the gypsum, forexample by sorting, has, up to this point, not been successfullyimplemented in technical production.

The coarse pre-pulverized material cannot be processed in theconventional calcination devices. The paper shreds would, in for examplean indirectly heated rotating pipe calcination device, float upon thegypsum grain bed to form balls which cannot be properly withdrawn andwhich, therefore, can clog the calcination device. There is also therisk that, when emptying the calcination device, dried paper remains inthe calcination device which, when repowering up, causes an explosion.

One had also introduced the coarsely pre-pulverized material togetherwith fresh natural gypsum into a mill. The up to 30 mm large naturalgypsum chips effect, in advantageous cases, a certain furtherpulverization of the shredded paper which, however, is not alwayssufficient. If small grain flue-gas gypsum or chemical gypsum isutilized as a raw material a satisfactory further pulverization is notpossible. The procedure has, therefore, not been practically successful.

SUMMARY OF THE INVENTION

In accordance with the invention, the known continuous-operation machineis utilized, following coarse pre-pulverization, for the processing ofwaste material coming from the production of gypsum plaster board.

The waste material flowing into the machine with the usage applicationin accordance with the invention is already pressed into a product-cyclepath in the entrance region. The waste material is, by means of thetools, processed in a spirally running product motion in theproduct-cycle in a surprisingly more uniform and more effective fashionthan achieved in the mills utilized up to this point and, at the sametime, is thereby homogenized.

By processed it is meant that the paper shreds are ground down to assmall an extent as possible and that the remaining waste material isreduced to primary grain size to as great an extent as possible. At theproduct exit, the processed material manifests a grain spectrum which isparticularly well suited for further processing in known calcinationdevices. The efficiency and the operational reliability of thesubsequent processing steps is, in this fashion, significantlyincreased. Furthermore, the materials processed in accordance with theinventive usage application are also particularly well suited for mixingwith fine raw gypsum.

With the inventive usage application it is also possible for fluids tobe brought into the product cycle. This is particularly advantageouswhen the degree of moisture desired for the processing operation has notyet been achieved and/or when a particular granularity or agglomerateformation is necessary.

In addition, a return region comprising spatially fixed baffle wallsand/or baffle rods, which are also useful for adding fluids, can beestablished in the processing volume which, together with the rotatingtools, can effect an additional shearing of the product.

In accordance with the inventive usage application, the mean dwell timeof the waste material in the container is very short. That is to say, amean dwell time of 15 seconds to 150 seconds is sufficient to break-upthe plate-sized coarse pulverized pieces of gypsum plaster board to asufficient extent that individual particle sizes are achieved, which canbe further processed without difficulty in a direct or indirectly heatedcalcination device.

If, in accordance with particular manufacturing conditions, it not bepossible to achieve the desired grain size spectrum in one machine atthe output of the machine, an additional machine can be positioned inseries in accordance with the inventive usage application; in thismachine, if required, additional dried material can also be mixed inwhile further breaking-up processing is carried out.

If the waste material to be processed is too moist, it is possible forthe shaft and/or the tools to be heated. If, frictional heat must, inaddition, be removed from the machine, it is also possible to cool theshafts or the tools. In the utilized machines, the tools are screwedinto shafts so that the free end of the tools, by screwing to a greateror lesser extent into the tool shaft, can be separated to a greater orlesser extent from the inner wall of the container in a simple fashion.

It is furthermore advantageous to so configure the cylindrical containerthat it consists of two half shells which are pivotable with respect toeach other. This allows a simple access and the tools, according to therequirements, can be rapidly exchanged.

As can be derived from German patent application P 41 24 984.4, themachine in accordance with the inventive usage application can also becombined with a plough-blade mixer which, on the one hand, providesadditional breaking-up action and, on the other hand, homogeneouslymixes the materials to be processed by the procedure so that they cansubsequently be introduced into a calcination device without anydifficulty.

It is also particularly advantageous when the pre-pulverization of thedefective gypsum plaster board is already untertaken in the entranceregion of the machine. With this configuration of differentlyfunctioning mechanisms, it is possible to achieve compact assemblyunits.

With the machine in accordance with the inventive usage application, itis also possible, in contrast to the teaching in accordance with P 41 24984.4, to satisfactorally carry out the reprocessing of defective gypsumplaster board without using cutter heads.

Further advantages can be derived from the description and theaccompanying drawing. Likewise the above-mentioned features as well asthose which will be additionally explained below in accordance with theinvention can each be utilized individually or collectively in arbitrarycombinations. The embodiments mentioned are not to be taken as exclusiveenumeration but rather have exemplary character only.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is represented in the drawing and will be furtherexplained in the embodiments.

FIG. 1 shows an overall view of a machine in the inventive usageapplication;

FIG. 2 shows a cut in accordance with II--II of FIG. 1;

FIG. 3 shows an embodiment of a configuration having a plurality ofmachines which can be utilized in the usage application in accordancewith the invention.

The individual figures of the drawing show the machines utilized inaccordance with the inventive usage application in a partially stronglyschematized fashion and are not to be taken to scale.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1, 1 is an overall view of a machine utilized in accordance withthe inventive usage application. Arrow 2 indicates the product flow asit passes through machine 1. Arrow 3 is the product flow for thehomogeneously broken-up waste material of the gypsum plaster board whenflowing out of the machine 1 in the processed state. The waste materialpasses through a container 4 along a spiral-shaped path. The product tobe processed is passed through machine 1 in a product-cycle and ispressed tightly onto the inner wall of the container. The container 4consists of a first half-shell 5 and a second half-shell 6. Thehalf-shells 5, 6 are connected to each other in such a fashion that theycan be pivoted with respect to each other. Container 4 has a shaft 7which is preferentially mounted via front walls 8, 9. In the FIG. 7indicates the shaft and 10 indicates the bearing. The shaft 7 itself isdriveable; the driving mechanisms suitable therefor are not shown inFIG. 1. Hand-screws 11 are provided for on the first and secondhalf-shells 5, 6 by means of which the half-shells 5, 6 can be heldtogether in a product-tight fashion. A product feed chute 12 isconfigured on the first half-shell 5 and a product exit chute 13 isprovided for on the second half-shell 6. In the figure, the container 4is provided with a jacket 14 by means of which the container 4 can beheated or cooled. Media such as water vapor, gases of various kinds andoil are suitable for heating or cooling. A directed temperatureadjustment can be used to control deposit formation within container 4.In the figure, feed connectors 15 and exit connectors 16 are representedfor the media. By means of mountings 17 it is possible to introducefluids into the product-cycle. The mountings 17, in particular pipes,can also function as baffle-rods to define a return zone. The pipes canexhibit cross sections of arbitrary polygonal shape. In the return zone,the material being processed can be subjected to additional shearingforces. Semicircular shaped plate-segment baffle walls can replace thebaffle rods.

Pulverizing instruments with individual drive mechanisms can be providedfor in the product feed chute 12 which can undertake a coarsepulverization of the waste material.

FIG. 2 shows the cut II--II of FIG. 1. Further features of the machinewhich are still visible in the background of the cut II--II such as handscrews 11, mountings 17 and the product feed chute 12 are notrepresented in the figure for reasons of clarity. The same objects aregiven the same reference symbols in the figures.

The sectional cut shows the shaft 7 with mounted tools 18, 18', 18" and18'". The tools 18, 18', 18", and 18'" consist of a shaft, into whichthe free cone-shaped ends of these tools are screwed. By means of thescrew, it is possible to easily adjust the separation of the free endsof the tools 18, 18', 18", 18'" relative to the inner wall of thevessel. The shaft 7 rotates in the direction of the arrow 19 along withtools 18, 18', 18" and 18'".

Due to the rotational speed of the tools 18, 18', 18" and 18'", thewaste material 20 is guided through the vessel 4 in a spiral-shapedfashion in the product-cycle. The product is thereby processed to suchan extent that a grain spectrum is achieved whose grain size allows forits use in the above mentioned calcination devices, without difficulty.The waste material 20 is indicated by dots in FIG. 2.

The half shells 5, 6 exhibit a jacket 14 by means of which the container4 can be heated or cooled. The shaft 7, represented in FIG. 2 as a solidshaft, can also be configured as a hollow shaft by means of whichheating or cooling media can be introduced to the tools 18, 18', 18" and18'". The tools 18, 18', 18" and 18'" are distributed in the axialdirection along the entire shaft 7. The first half-shell 5 is pivotablewith respect to the spacially fixed second half-shell 6. Arrows 19' and19" indicate the pivot direction. The pivot bearing on the one side ofthe container 4, the closing mechanism on the other side, and the handscrews 11, are not shown in the figure.

FIG. 3 shows a machine configuration 25, by way of example, as it can beutilized in the inventive usage application. A first machine 26,described in accordance with the inventive usage application, and asecond machine 27 are connected in series with a plough-blade mixer 28which is per se known in the art. The waste material to be processedflows in the direction of arrows 29, 29', 29", 29'" through the machineconfiguration 25. The individual machines 26, 27 and the plough-blademixer 28 are driven by symbolically represented drive mechanisms 30,30', 30". Additional pulverizing tools can be provided for in theproduct feed chute 31 which are not shown in the figure and theprocessed waste material is fed into a calcination device, which is perse known in the art, via product exit chute 32. The machineconfiguration 25 shown in the figure can also have additional machinesattached thereto according to need.

Usage application of a per se known in the art continuous-operationmachine for the recycling of gypsum plaster board. A coarselypre-pulverized material is introduced into a continuous-operationmachine and, within the continuous-operation machine, the waste material20 is guided along a product-cycle in a spiral-shaped fashion throughthe container 4 The tools 18, 18', 18", 18'", which are arranged alongan axial length on the shaft 7, rotate in a Froude number region Fr≧7and break-up the pre-pulverized waste material 20 to a sufficient extentthat a grain spectrum is produced which effectively facilitates the useof calcination devices.

We claim:
 1. A method for the continuous-operation of a machine torecycle gypsum plaster board waste material comprising the stepsof:coarsely pre-pulverizing the waste material; feeding the coarselypre-pulverized waste material into a feed chute of a horizontallypositioned, cylindrical container having an exit chute; driving a shaftin the container in a Froude number range Fr≧7; grinding the wastematerial with tools which are radially mounted on the shaft; andintroducing the waste material into a further processing device torecycle the waste material.
 2. The method of claim 1, wherein a meandwell time of the waste material in the container assumes a valuebetween 15 to 150 seconds.
 3. The method of claim 1, further comprisingat least one of heating and cooling at least one of the shaft and thetools.
 4. The method of claim 1, further comprising accessing the insideof the cylindrical container by pivoting two half-shells which form thecontainer.
 5. The method of claim 1, further comprising:pulverizing andhomogenizing the waste material in a first machine; and mixing thehomogenized, pulverized waste material with additional bulk material ina second machine.
 6. The method of claim 1, further comprising feedingthe processed waste material from the container into acontinuous-operation mixer for further processing.
 7. The method ofclaim 1, wherein the further processing device comprises an indirectlyor directly heatable calcination device.
 8. The method of claim 1,wherein the course pre-pulverization takes place in the vicinity of aproduct feed chute.
 9. The method of claim 1, further comprising feedingfluids through container mountings into the container.
 10. A method forthe continuous-operation of a machine to recycle gypsum plaster boardwaste material comprising the steps of:coarsely pre-pulverizing thewaste material; feeding the coarsely pre-pulverized waste material intoa feed chute of a horizontally positioned, cylindrical container havingan exit chute; driving a shaft in the container in a Froude number rangeFr≧7; grinding the waste material with tools which are radially mountedon the shaft to press the waste material against an inner wall of thecylindrical container, to pass the waste material along a spiral pathfrom the feed chute to the exit chute, and to homogenize the wastematerial; discharging the waste material through the exit chute; andintroducing the waste material into a further processing device torecycle the waste material.
 11. A method for the continuous-operating ofa machine to recycle gypsum plaster board waste material comprising thesteps of:coarsely pre-pulverizing the waste material; feeding thecoarsely pre-pulverized waste material into a feed chute of ahorizontally positioned, cylindrical container having an exit chute;driving a shaft in the container in a Froude number range Fr≧7; grindingthe waste material with tools which are radially mounted on the shaft topress the waste material against an inner wall of the cylindricalcontainer, to pass the waste material along a spiral path from the feedchute to the exit chute, and to homogenize the waste material;discharging the waste material through the exit chute; and introducingthe waste material into an indirectly or directly heatable calcinationdevice to recycle the waste material.